Turkey and the fixins aren't the only things people will be digesting over the Thanksgiving and upcoming Christmas holidays.

Expect more spam. Lots more. It's a recurring theme seemingly as inevitable as Christmas carols and fruitcake, as internetnews.com has reported in 2002, 2003 and 2004.

Security experts at anti-spam and anti-virus vendor AppRiver expect the volume of spam to double during the holidays. The irritating messages accounted for 81 percent of all e-mails its customers saw in August. But spammers pull out all the stops for the holiday deluge, with good reason.

The reason for the surge, said Joel Smith, AppRiver CTO, is because spammers know that people are much more likely to click on a potential deal than at any other time of the year. In other words, while people may know it's an unsolicited e-mail and would likely trash it any other time of the year, the chance to pick up a present on the cheap is too hard to resist for the spamee during the holiday season.

"Spammers wouldn't send as much during this time if they didn't get good results as well," Smith said.

AppRiver culled some of the e-mail subject lines that are being used to lure potential customers in, they include:

"Send the kids a letter from Santa"

"Holiday Hint #1: Shop Now, Get Free Shipping"

"Holiday Treats and a free gift from Jelly Belly"

One of the trends AppRiver officials see with spam is that while many of the offers feature the generic replica watches, weight loss pills and the like, spammers are including name-brand items to give the e-mails a hint of legitimacy.

The expected spam surge also likely coincides with the recent rash of viruses spreading throughout the Internet.

The FBI released an advisory Tuesday warning consumers of e-mail purportedly coming from the agency but are in fact spoofed e-mails containing a variant of the Sober virus.

The spoof claims the FBI has tracked the user's IP address to a number of illegal Web sites and tells them to open an attachment containing what the e-mail states are a list of questions to answer.

AppRiver is tracking two Sober variants, Sober.z and Sober.gen, which they said on Tuesday accounted for 32 percent of all the viruses blocked by the company. Officials said the variants are the most intense outbreak in the past six months, with 24,000 instances of the Sober.z and 48,000 instances of the Sober.gen blocked Monday.

Smith said it's no coincidence there's a rash of viruses leading up to the holiday season. They're an attempt, he said, to give spammers more reach in spreading their holiday messages.

"It's all related, it's all an attempt to get fresh zombied computers to prepare to make blasts for the holiday shopping season," Smith said.